Semiconductor producing processes use various processing systems, such as semiconductor producing systems and inspection systems. These processing systems are designed to use various operation data to monitor their operation states. If the operation states are considered to be abnormal, it is necessary to diagnose causes. When diagnosing the causes, the various operation data are collected and analyzed for grasping the operation states of the processing systems, to examine the place of abnormality.
For example, a plasma processing system is used for etching, deposition or the like. For example, a plasma processing system of this type comprises top and bottom electrodes which are provided in parallel in a processing vessel, and is designed to apply a high frequency power to the bottom electrode and feed a process gas into the processing vessel to apply predetermined plasma-processing to an object to be processed, such as a semiconductor wafer. Then, the plasma processing system is designed to detect over thirty kinds of data, such as pressure in the processing vessel, voltage applied to the bottom electrode, and the supply flow rate of the process gas, by means of detectors, respectively, to utilize the respective detected values as operation data to monitor the operation state of the processing system.
However, if the processing system continues a predetermined processing for a long time, the operation state varies with time, or the operation state suddenly varies in some cases. In such cases, statistical data, such as mean, maximum, minimum and variance values, are separately obtained with respect to the operation data, such as the high frequency power, the flow rate of the process gas and the pressure of the process gas in the processing vessel, and the operation state of the processing system is evaluated on the basis of the respective statistical data. However, since the number of detectors is large, there is a problem in that it is complicated and takes a lot of time to obtain the statistical data with respect to the operation data of all the detectors to evaluate the operation data every detector.
For example, when new processing systems or processing systems after maintenance are evaluated, the trial run of each of the processing systems is carried out. Then, operation data obtained by the trial run are compared with operation data obtained by a corresponding detector of a processing system as a reference (which will be hereinafter referred to as a “reference processing system”), one by one as shown in FIGS. 11 through 15, and are analyzed. Therefore, there is a problem in that it takes a lot of time to evaluate such a processing system.
Then, for example, the plasma processing system of this type applies a high frequency power to the electrodes in the processing vessel and feeds a process gas into the processing vessel to produce plasma of the process gas in the processing vessel to carry out a predetermined plasma processing with respect to a object to be processed, such as a semiconductor wafer. In this case, the object is processed after a high frequency source for supplying the high frequency power is stabilized in accordance with the state in the processing vessel. However, immediately after the processing system is started, the high frequency source is unstable and is not stabilized for a long time until the high frequency source adapts itself to the state in the processing vessel.
For example, FIG. 23a is a graph showing the variation of a parameter (voltage) relating to the high-frequency waves of a matching circuit, and FIG. 23b is a graph showing the variation of a parameter (capacitance) of a capacitor characterizing the matched state of the matching circuit. Both of the parameters vary with time, so that it is difficult to determine the stable condition. For example, in the parameter shown in FIG. 23a, a peak appears at the beginning of a series of the wafers, but it is difficult to determine whether the parameter is stabilized. It also takes a lot of time until the inside of the processing vessel adapts itself to environment wherein the high frequency power has been applied, and the inside of the processing vessel is not stable for a long time. Therefore, it is conventionally determined by operator's experience and intuition whether the states of the high frequency source and the inside of the processing vessel are stabilized. FIGS. 8a and 8b show the results on an operating condition on which the amount of deposition is small, after the processing vessel is evacuated for four days after the system is provided with maintenance and inspected. This condition on which the amount of deposition is small will be described later.
Thus, there is no technique for objectively determining whether the high frequency source and inside of the processing vessel of the processing system are stabilized, and it must be relied on operator's experience and intuition. Since it is not possible to evaluate processing conditions for leading the processing system to its stable condition, the evaluation must be relied on trial-and-error.
When the processing system is provided with maintenance and inspected, consumable goods are exchanged, and cleaning is carried out. However, since the processing system is a precision instrument, it is required to pay close attention to the assembly of the processing system. For example, even if there is slight loosening of screwing for the respective parts of the high frequency source and in the processing vessel, or even if there are slight errors, such as errors in the mounting of part of parts, plasma is unstable. However, conventionally, if the processing system is operated without finding such errors, there is no technique for identifying the errors without opening and inspecting the processing system, so that it takes a lot of time to diagnose the causes.